Nowadays, the access to Internet content data (such as video, audio) has increased significantly due to the adoption to smart phones and tablets. When Internet video is accessed by a mobile device (it also could be called UE, User Equipment), the video has to be fetched from the servers of a CDN (Content Delivery Network).
CDNs are used to help reduce Internet bandwidth consumption and associated delay/jitter. Thereby the quality of experience is improved. CDN system has evolved wherein caches are placed at a RAN (Radio Access Network) and most of video requests can be served from caches of the RAN instead of having to be fetched from the Internet CDNs.
FIG. 1 is a topology diagram showing a structure of CDN deployment. As shown in FIG. 1, caches are placed at a CN (Core Network) and also nodes of the RAN.
The existing approach (as shown in FIG. 1) enables caching of videos at the edge of the RAN such that most video request can be served from the caches of RAN, instead of having to be fetched from the Internet CDNs. This will lead to thousands of caches, wherein each RAN node has a cache having smaller size.
Theses caches serve video request without requiring the traffic to be routed via the CN. If cache miss happens on RAN (such as in an eNB), data will be fetched from next level, such as a P-GW (Packet GateWay) in the CN or a SP (Service Provider) in the CDN.
However, the applicant found that: the content data (such as video) must additionally travel through the wireless carrier CN and RAN before reaching the mobile device. Besides adding to video latency, bringing each requested video from the Internet CDNs can put significant strain on the carrier's CN and RAN backhaul. This will lead to congestion, significant delay, and constraint on the network's capacity to serve large number of concurrent video requests.
The main issues with the current approach are: RAN caches can store only thousands of videos as compared to much larger sized caches used in internet CDNs which can store millions of videos, thereby affecting cache hit ratio. In some scenario, RAN cache miss happens while the required data may be present in neighboring nodes. However, the data needs to be retrieved from CN or Internet CDNs which adds strain on carrier's CN and RAN backhaul.